According to one embodiment, there is provided a disk device including a head and a controller. The controller, with mapping information in which parameter sets each including multiple types of parameters related to operations of the head are mapped to an adjustment variable so as to be associated with multiple different values of the adjustment variable, evaluates operations of the head while changing the value of the adjustment variable contained in the mapping information and determines a parameter set corresponding to an appropriate value of the adjustment variable based on the evaluation results and the mapping information to set for operations of the head using the determined parameter set.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A disk device comprising: a head; and a controller that, with mapping information in which parameter sets each including multiple types of parameters related to operations of the head are mapped to an adjustment variable so as to be associated with multiple different values of the adjustment variable, evaluates operations of the head while changing the value of the adjustment variable contained in the mapping information and determines a parameter set corresponding to an appropriate value of the adjustment variable based on the evaluation results and the mapping information to set for operations of the head using the determined parameter set.
2. The disk device according to claim 1 , further comprising a disk medium that can be accessed by the head, wherein in the mapping information, the parameter sets related to write operations of the head are mapped to the adjustment variable so as to be associated with multiple different values of the adjustment variable, and wherein the controller reads, by the head, information written on the disk medium by the head to evaluate signal quality while changing the value of the adjustment variable and determines a parameter set corresponding to an appropriate value of the adjustment variable based on the evaluation results and the mapping information to set for write operations of the head using the determined parameter set.
3. The disk device according to claim 1 , further comprising a disk medium that can be accessed by the head, wherein in the mapping information, the parameter sets related to read operations of the head are mapped to the adjustment variable so as to be associated with multiple different values of the adjustment variable, and wherein the controller reads, by the head, information written on the disk medium by the head to evaluate signal quality while changing the value of the adjustment variable and determines a parameter set corresponding to an appropriate value of the adjustment variable based on the evaluation results and the mapping information to set for read operations of the head using the determined parameter set.
4. The disk device according to claim 2 , wherein in the mapping information, the parameter sets related to write current waveforms of the head are mapped to the adjustment variable related to integral values of write currents of the head so as to be associated with multiple different values of the adjustment variable.
5. The disk device according to claim 3 , wherein in the mapping information, the parameter sets related to read signal of the head are mapped to the adjustment variable related to usage bands of read signal of the head so as to be associated with multiple different values of the adjustment variable.
6. The disk device according to claim 4 , wherein the adjustment variable is a value obtained by integrating the value of a write current over a period from a zero-cross timing of the write current of the head until the timing when a predetermined time elapses.
7. The disk device according to claim 5 , wherein the adjustment variable is the upper limit of the usage band of a read signal of the head.
8. The disk device according to claim 1 , wherein the mapping information includes a table in which the parameter sets are mapped to the adjustment variable so as to be associated with multiple different values of the adjustment variable.
9. The disk device according to claim 1 , wherein the mapping information includes multiple functions denoting relations between multiple types of parameters included in the parameter set and the adjustment variable.
10. The disk device according to claim 1 , wherein the controller acquires multiple candidate parameter sets that are candidates to be associated with the adjustment variable and measures the value of the adjustment variable multiple times for each of the multiple candidate parameter sets and associates a candidate parameter set for which variation in the value of the adjustment variable is smallest from among the multiple candidate parameter sets, according to the measuring results, with the value of the adjustment variable so as to create the mapping information.
11. The disk device according to claim 10 , wherein the controller measures the value of the adjustment variable multiple times for each of the multiple candidate parameter sets and obtains a second adjustment variable indicating a standard deviation of the value of the adjustment variable measured multiple times for each of the multiple candidate parameter sets and associates a candidate parameter set for which the value of the second adjustment variable is smallest from among the multiple candidate parameter sets with the value of the adjustment variable so as to create the mapping information.
12. The disk device according to claim 1 , further comprising a preamplifier placed between the head and the controller, wherein the controller stores the determined parameter set in the preamplifier to set for operations of the head.
13. A preamplifier comprising: a storage circuit that can store multiple values of an adjustment variable contained in mapping information out of the mapping information in which parameter sets each including multiple types of parameters related to operations of the head are mapped to the adjustment variable so as to be associated with multiple different values of the adjustment variable; a determining circuit that evaluates operations of the head for the multiple values stored in the storage circuit and determines a parameter set corresponding to an appropriate value of the adjustment variable based on the evaluation results and the mapping information; and a setting circuit that sets for operations of the head using the determined parameter set.
14. The preamplifier according to claim 13 , wherein in the mapping information, the parameter sets related to write operations of the head are mapped to the adjustment variable so as to be associated with multiple different values of the adjustment variable, wherein the determining circuit reads, by the head, information written on the disk medium by the head to evaluate signal quality while changing the value of the adjustment variable and determines a parameter set corresponding to an appropriate value of the adjustment variable based on the evaluation results and the mapping information, and wherein the setting circuit sets for write operations of the head using the determined parameter set.
15. The preamplifier according to claim 14 , wherein in the mapping information, the parameter sets related to write current waveforms of the head are mapped to the adjustment variable related to integral values of write currents of the head so as to be associated with multiple different values of the adjustment variable.
16. The preamplifier according to claim 15 , wherein the adjustment variable is a value obtained by integrating the value of a write current over a period from a zero-cross timing of the write current of the head until the timing when a predetermined time elapses.
17. The preamplifier according to claim 13 , wherein the mapping information includes a table in which the parameter sets are mapped to the adjustment variable so as to be associated with multiple different values of the adjustment variable.
18. The preamplifier according to claim 13 , wherein the mapping information includes multiple functions denoting relations between multiple types of parameters included in the parameter set and the adjustment variable.
19. The preamplifier according to claim 13 , wherein the determining circuit acquires multiple candidate parameter sets that are candidates to be associated with the adjustment variable and measures the value of the adjustment variable multiple times for each of the multiple candidate parameter sets and associates a candidate parameter set for which variation in the value of the adjustment variable is smallest from among the multiple candidate parameter sets, according to the measuring results, with the value of the adjustment variable so as to create the mapping information.
20. A control method of a disk device including a head, comprising: with mapping information in which parameter sets each including multiple types of parameters related to operations of the head are mapped to an adjustment variable so as to be associated with multiple different values of the adjustment variable, evaluating operations of the head while changing the value of the adjustment variable contained in the mapping information; determining a parameter set corresponding to an appropriate value of the adjustment variable based on the evaluation results and the mapping information; and setting for operations of the head using the determined parameter set.
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September 7, 2018
June 18, 2019
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